UNITED STATES DEPARTMENT OF AGRICULTURE 
m BULLETIN No. 916 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
June 13, 1921 
FREEZING INJURY TO POTATOES WHEN 
UNDERCOOLED. 1 
By R. C. Wright, Physiologist, and George F. Taylor, Chemical Laooratorian^ 
Office of Horticultural and Pomological Investigations. 
CONTENTS. 
Page. 
Scope of the investigations 1 
Physiology of the freezing process 2 
Plan of the work. 
Page. 
Inoculation of unaercooled potatoes- 7 
Summary ' . 14 
4 I Literature cited. 
15 
SCOPE OF THE INVESTIGATIONS. 
Each year the loss to growers, shippers, and carriers of potatoes 
due to freezing reaches an enormous figure. This is particularly 
true of the late or main crop produced in the Northern States. This 
crop is usually in constant danger of exposure to freezing tempera- 
ture from just before it is harvested until it reaches the consumer. 
There are two general classes of frost-injured potatoes — those frozen 
solid and subject to collapse immediately on thawing and those that 
show evidence of injury only on being cut open a few hours after 
being warmed. The first class of injured potatoes is easily identified 
by the soft, wet condition that develops on thawing. This type of 
injury is due to the potato being subjected to freezing at very low 
temperatures or to prolonged exposure at higher freezing tempera- 
tures. The second type of injury is not apparent on superficial ex- 
amination. It is due to exposure to temperatures just below the 
freezing point or to a very low temperature for a short time. If after 
the potato has been thawed a few hours it is cut open, evidences of 
this type of freezing injury are apparent by the presence of vascular 
discoloration of three types or a combination of any of the three. 
1 This bulletin gives the results of a portion of the work carried on under the project 
" Factors affecting the storage life of vegetables." 
11310°— 21 
